Consider the following diagram. The first site (Remote1) is equipped with a Cisco ASA firewall (any model) and the second site (Remote2) is equipped with a Cisco Router. Remember that a Cisco ASA firewall is by default capable to support IPSEC VPN but a Cisco Router must have the proper IOS software type in order to support encrypted VPN tunnels.

Equipment Used in this LAB:

• ASA 5510 – Cisco Adaptive Security Appliance Software Version 8.0(3)

• Cisco Router 2801 – C2801-ADVIPSERVICESK9-M Version 12.4(9)T4

Scenario:

LAN of Remote1 must be connected to LAN of Remote2 via VPN Tunnel. The most usual scenario is that the WAN cloud is the Internet, so secure connectivity shall be provided between the two LAN networks over the Internet.

First of all we shall make sure that the outside interfaces of ASA and router must be reachable over the WAN. Now let’s start IPSEC VPN configuration.

Cisco ASA Configuration

First I started ASA configuration.

I’ve created an Access list, which will match the interesting traffic which is the traffic to be encrypted. If source is 192.168.3.0/24 and destination is 192.168.4.0/24, then traffic will be matched by the access list as “interesting traffic” and will be encrypted and pass through the tunnel.

ASA(config)# access-list vpn extended permit ip 192.168.3.0 255.255.255.0 192.168.4.0 255.255.255.0

!IKE PHASE #1
! I’ve created a phase1 policy. This policy provides secured process of exchanging Keys.
ASA(config)# crypto isakmp policy 1

! For authentication I used Pre-shared. This method is most frequently used today.
ASA(config)# authentication pre-share

!For encryption I used 3des.
ASA(config)# encryption 3des

! Hashing md5.
ASA(config)# hash md5

! I used second group of diffie-hellman. Group1 is used by default. The most secured is Group5.
ASA(config)# group 2

! configure crypto key. The keys must match to each other between peers. Otherwise Phase1 will not be completed.
ASA(config)# crypto isakmp secretsharedkey address 192.168.2.2

NOTE: Crypto key is hidden in ASA configuration. If we look at configuration, it will be shown in following way.
tunnel-group 192.168.2.2 ipsec-attributes
pre-shared-key *

! Activate policy on Outside interface.
ASA(config)# crypto isakmp enable outside

! IKE PHASE #2- VPN Tunnel is established during this phase and the traffic between VPN Peers is encrypted according to the security parameters of this phase.

! I created Transform-set, by which the traffic will be encrypted and hashed between VPN peers.
ASA(config)# crypto ipsec transform-set ts esp-3des esp-md5-hmac

! Apply the access list created earlier for matching the interesting traffic.
ASA(config)# crypto map vpn 10 match address vpn

! I indicated address of Remote2 peer public outside interface.
ASA(config)# crypto map vpn 10 set peer 192.168.2.2

! Apply also the transform-set.
ASA(config)# crypto map vpn 10 set transform-set ts

! Attach the already created Crypto-map and VPN to outside interface.
ASA(config)# crypto map vpn interface outside

ASA configuration is completed here (regarding the VPN config of course). Now let’s start Router Configuration below.

Cisco Router Configuration

ISAKMP Phase 1

! Enter crypto-isakmp policy configuration mode for configuring crypto isakmp policy.
Router(config)# crypto isakmp policy 10

! Turn on 3des as an encryption type.
Router(config)# encr 3des

! I indicated MD5 as a hashing type.
Router(config)# hash md5

! I indicated pre-share authentication.
Router(config)# authentication pre-share

! I used second group of diffie-hellman. group1 is used by default.
Router(config)# group 2

! I defined peer key same as ASA site.
Router(config)# crypto isakmp secretsharedkey address 192.168.1.2

It’s not necessary to match policy numbers. The most important is to match corresponding parameters of policy. Otherwise negotiation of Phase1 will not be successful.

! Access list for matching interesting traffic.
Router(config)# ip access-list extended vpn
Router(config)# permit ip 192.168.4.0 0.0.0.255 192.168.3.0 0.0.0.255

ISAKMP PHASE 2
!
! Create IPSEC transform-set, by which the mechanism of hashing and encryption is determined, by which the traffic will be hashed/encrypted in VPN tunnel later.
Router(config)# crypto ipsec transform-set ts esp-3des esp-md5-hmac

! Enter into crypto-map configuration mode.
Router(config)# crypto map vpn 10 ipsec-isakmp

! Indicate IP address of peer.
Router(config)# set peer 192.168.1.2

! Indicate IPsec transform-set created above.
Router(config)# set transform-set ts

! Apply access list created above.
Router(config)# match address vpn

! Apply crypto-map to interface.
Router(config)# interface FastEthernet0/0
Router(config)# crypto map vpn

With this, VPN configuration is completed so let’s start verification.

! In the output below it is shown that ISAKMP PHASE1 is active, which means that negotiation of PHASE1 is completed successfully.

ASA# show crypto isakmp sa

Active SA: 1
Rekey SA: 0 (A tunnel will report 1 Active and 1 Rekey SA during rekey)
Total IKE SA: 1

1 IKE Peer: 192.168.2.2
Type : L2L Role : initiator
Rekey : no State : MM_ACTIVE

Router# show crypto isakmp sa
dst src state conn-id slot
192.168.1.2 192.168.2.2 MM_ACTIVE 1 0

! Checking ISAKMP PHASE2. Here we see that IPSec is working and the interesting traffic flows in VPN Tunnel.

ASA# show crypto ipsec sa
interface: outside
Crypto map tag: vpn, seq num: 10, local addr: 192.168.1.2

access-list vpn permit ip 192.168.3.0 255.255.255.0 192.168.4.0 255.255.255.0
local ident (addr/mask/prot/port): (192.168.3.0/255.255.255.0/0/0)
remote ident (addr/mask/prot/port): (192.168.4.0/255.255.255.0/0/0)
current_peer: 192.168.2.2

#pkts encaps: 344, #pkts encrypt: 344, #pkts digest: 344
#pkts decaps: 344, #pkts decrypt: 344, #pkts verify: 344
#pkts compressed: 0, #pkts decompressed: 0
#pkts not compressed: 344, #pkts comp failed: 0, #pkts decomp failed: 0
#pre-frag successes: 0, #pre-frag failures: 0, #framents created: 0
#PMTUs sent: 0, #PMTUs rcvd: 0, #decapsulated frgs needing reassembly: 0
#send errors: 0, #recv errors: 0

Router# show crypto ipsec sa

interface: FastEthernet0/0
Crypto map tag: vpn, local addr 192.168.2.2

protected vrf: (none)
local ident (addr/mask/prot/port): (192.168.4.0/255.255.255.0/0/0)
remote ident (addr/mask/prot/port): (192.168.3.0/255.255.255.0/0/0)
current_peer 192.168.1.2 port 500
PERMIT, flags={origin_is_acl,}
#pkts encaps: 344, #pkts encrypt: 344, #pkts digest: 344
#pkts decaps: 344, #pkts decrypt: 344, #pkts verify: 344
#pkts compressed: 0, #pkts decompressed: 0
#pkts not compressed: 0, #pkts compr. failed: 0
#pkts not decompressed: 0, #pkts decompress failed: 0
#send errors 0, #recv errors 0

VPN Tunnel is established and works.

Related posts:

1. Cisco Router with Cisco ASA for Internet Access
2. How To Configure AnyConnect SSL VPN on Cisco ASA 5500
3. VPN client Error -Syslog ID 305006

So basically the ASA uses regular expressions (regex) together with Modular Policy Framework to inspect specific HTTP data patterns in order to detect the SQL injection attack. It will basically check for the SQL command “UNION ALL SELECT”.

Below is the configuration as described on the Cisco support forum:

regex SQL_regex_1 “[uU][nN][iI][oO][nN]([%]2[0bB]|[+])([aA][lL][lL]([%]2[0bB]|[+]))?[sS][eE][lL][eE][cC][tT]“
regex SQL_regex_2 “[Ss][Ee][Ll][Ee][Cc][Tt](%2[0bB]|+)[^\r\x00-\x19\x7f-\xff]+(%2[0bB]|+)[Ff][Rr][Oo][Mm](%2[0bB]|+)”
!
class-map WebServers
match port tcp eq www
class-map type inspect http match-any SQL-map
match request body regex SQL_regex_1
match request body regex SQL_regex_2
!
policy-map type inspect http drop-SQL
parameters
body-match-maximum 3000
class SQL-map
drop-connection log
policy-map SQL-traffic
class WebServers
inspect http drop-SQL
!
service-policy SQL-traffic interface outside

We assume that our webserver is protected on a DMZ zone on the ASA. Traffic is coming from the outside so the service policy (SQL-traffic) is applied on the outside. Upon a regular expression match, the ASA will drop the HTTP connection and generate a log. The above is a just a starting point for SQL attack protection and can not defend against all attacks. For example if the SQL statement is Hex encoded or url encoded by the attacker, the regex will not detect it. Here is the link from Cisco forum for more information:

https://supportforums.cisco.com/docs/DOC-14890

Related posts:

1. Traffic Rate Limiting on Cisco ASA
2. Block Attacks with a Cisco ASA Firewall and IDS using the shun command
3. DNS Security Protection Parameters

Configuration

!First identify the DHCP server and the interface it Is connected to
ciscoasa# conf t
ciscoasa(config)# dhcprelay server 10.1.1.100 DMZ
ciscoasa(config)# dhcprelay timeout 90

!Now enable the DHCP relay on the inside interface
ciscoasa(config)# dhcprelay enable inside

!Assign the ASA inside interface IP as default gateway for the clients
ciscoasa(config)# dhcprelay setroute inside

Usage Guidelines

You can add up to four DHCP relay servers per interface. You must add at least one dhcprelay server command to the ASA Firewall configuration before you can enter the dhcprelay enable command. You cannot configure a DHCP client on an interface that has a DHCP relay server configured.

You cannot enable DHCP relay under the following conditions:
• You cannot enable DHCP relay and the DHCP relay server on the same interface.
• You cannot enable DCHP relay and a DHCP server (dhcpd enable) on the same interface.

Related posts:

1. How to Configure SNMP on Cisco ASA 5500 Firewall
2. Configure Static Routing on Cisco ASA Firewall
3. Configure Cisco ASA 5505 to allow Remote Desktop access from Internet

SECURITY APPLIANCE ACCESS MODES
A Cisco ASA security appliance has four main administrative access modes:

• Monitor Mode: Displays the monitor> prompt. A special mode that enables you to update the image over the network or to perform password recovery. While in the monitor mode, you can enter commands to specify the location of a TFTP server and the location of the software image or password recovery binary image file to download. You access this mode by pressing the “Break” or “ESC” keys immediately after powering up the appliance.
• Unprivileged Mode: Displays the > prompt. Available when you first access the appliance. If the appliance is a Cisco PIX 500 series, the prompt for unprivileged mode is pixfirewall> and if the appliance is the new Cisco ASA 5500 Series, the prompt is ciscoasa>

This mode provides restricted view of the security appliance. You cannot configure anything from this mode. To get started with configuration, the first command you need to know is the enable command. Type enable and hit Enter. The initial password is empty, so hit Enter again to move on the next access mode (Privileged Mode).

• Configuration Mode: This mode displays the (config)# prompt. Enables you to change all system configuration settings. Use exit from each mode to return to the previous mode.

The (config)# mode is sometimes called Global Configuration Mode. Some configuration commands from this mode enter a command-specific mode and the prompt changes accordingly. For example the interface command enters interface configuration mode as shown below:

ciscoasa(config)# interface GigabitEthernet0/1
ciscoasa(config-if)# <– Configure Interface specific parameters

Related posts:

1. Password Recovery for the Cisco ASA 5500 Firewall
2. How to Configure Access Control Lists on a Cisco ASA 5500 Firewall
3. How to Configure Access Control Lists on a Cisco ASA 5500 Firewall

Routed Firewall Mode:

See the diagram below for a common network topology of a Cisco ASA firewall working in Routed Mode.

As you can see, there are two different network subnets. Inside network (10.20.20.0/24) and Outside Network (10.10.10.0/24). There must be also two different layer2 vlans (Vlan20 for inside network and Vlan10 for outside network). All hosts residing in internal network must belong to subnet 10.20.20.0 and must have default gateway the internal IP of the ASA (10.20.20.1).

Transparent Firewall Mode:

The diagram below shows an example topology using a Cisco ASA in Layer 2 transparent mode.

As you can see, there is only one Layer 3 network (10.10.10.0/24) BUT there MUST be two different Layer 2 Vlans (Vlan20 for inside zone and Vlan10 for outside zone). All hosts must reside in network range 10.10.10.0 and the devices must have as default gateway the IP address of the outside router (10.10.10.2). Also, a management IP address MUST be configured on the ASA firewall (again within the range of 10.10.10.0). DO NOT specify the management IP address of the ASA as the default gateway for connected devices.

Initial Configuration

Asa(config)# firewall transparent

!Configure management IP below
Asa(config)# ip address 10.10.10.1 255.255.255.0

Asa(config)# interface Ethernet0/0
Asa(config-if)# nameif outside
Asa(config-if)# security-level 0
!
Asa(config)# interface Ethernet0/1
Asa(config-if)# nameif inside
Asa(config-if)# security-level 100

Related posts:

1. How to configure DHCP Relay on Cisco ASA Firewall
2. Cisco ASA Multiple Context Mode – Configuring Virtual Firewalls on Same Chassis
3. Configure Static Routing on Cisco ASA Firewall

However, the core ASA functionality is to work as a high performance firewall. All the other security features are just complimentary services on top of the firewall functionality. Having said that, the purpose of a network firewall is to protect computer and IT resources from malicious sources by blocking and controlling traffic flow. The Cisco ASA firewall achieves this traffic control using Access Control Lists (ACL).

The ACL permit or deny statements basically consist of source and destination IP addresses and ports. A permit ACL statement allows the specified source IP address/network to access the specified destination IP address/network. The opposite happens for deny ACL statements. At the end of the ACL, the firewall inserts by default an implicit DENY ALL statement rule which is not visible in the configuration.

Enough theory so far. Let us see some examples below to clarify what we have said above.

The basic command format of the Access Control List is the following:

ciscoasa(config)# access-list “access_list_name” extended {deny | permit} protocol “source_address” “mask” [source_port] “dest_address” “mask” [ dest_port]

To apply the ACL on a specific interface use the access-group command as below:

ciscoasa(config)# access-group “access_list_name” [in|out] interface “interface_name”

Example1:

Allow only http traffic from inside network 10.0.0.0/24 to outside internet

ciscoasa(config)# access-list HTTP-ONLY extended permit tcp 10.0.0.0 255.255.255.0 any eq 80

ciscoasa(config)# access-group HTTP-ONLY in interface inside

The name “HTTP-ONLY” is the Access Control List itself, which in our example contains only one permit rule statement. Remember that there is an implicit DENY ALL rule at the end of the ACL which is not shown by default.

Example2:

Deny telnet traffic from host 10.1.1.1 to host 10.2.2.2 and allow everything else.

ciscoasa(config)# access-list DENY-TELNET extended deny tcp host 10.1.1.1 host 10.2.2.2 eq 23

ciscoasa(config)# access-list DENY-TELNET extended permit ip host 10.1.1.1 host 10.2.2.2

ciscoasa(config)# access-group DENY-TELNET in interface inside

The above example ACL (DENY-TELNET) contains two rule statements, one deny and one permit. As we mentioned above, the “access-group” command applies the ACL to an interface (either to an inbound or to an outbound direction).

Example3:

The example below will deny ALL TCP traffic from our internal network 192.168.1.0/24 towards the external network 200.1.1.0/24. Also, it will deny HTTP traffic (port 80) from our internal network to the external host 210.1.1.1. All other traffic will be permitted from inside.

ciscoasa(config)# access-list INSIDE_IN extended deny tcp 192.168.1.0 255.255.255.0 200.1.1.0 255.255.255.0

ciscoasa(config)# access-list INSIDE_IN extended deny tcp 192.168.1.0 255.255.255.0 host 210.1.1.1 eq 80

ciscoasa(config)# access-list INSIDE_IN extended permit ip any any

ciscoasa(config)# access-group INSIDE_IN in interface inside

Related posts:

1. How to Configure Access Control Lists on a Cisco ASA 5500 Firewall
2. How to Create and Manage Access Control Lists on Cisco ASA
3. Access Lists and NAT on Cisco ASA Firewalls. Some Clarifications

Suppose we have a few Web servers located on a DMZ which are accessed from the Internet. We want to enable http (80) and https (443) access from internet towards these web servers.

Assume that we have configured static NAT for those web servers and translated their real private IP addresses to the following Public IP addresses:

Web Server1: 50.50.50.1
Web Server2: 50.50.50.2
Web Server3: 50.50.50.3

Configuration of access list using object groups:

! create a service group for the http and https protocols
object-group service http-protocols tcp
port-object eq 80
port-object eq 443

! create a network object group for the web servers
object-group network webservers
network-object host 50.50.50.1
network-object host 50.50.50.2
network-object host 50.50.50.3

! create the access list applied inbound on the outside interface
access-list OUTSIDE-IN extended permit tcp any object-group webservers object-group http-protocols

access-group OUTSIDE-IN in interface outside

Related posts:

1. Cisco Router with Cisco ASA for Internet Access
2. Access Lists and NAT on Cisco ASA Firewalls. Some Clarifications
3. Configure Cisco ASA 5505 to allow Remote Desktop access from Internet

The Cisco ASA 5500 is the new Cisco firewall model series which followed the successful Cisco PIX firewall appliance. Cisco calls the ASA 5500 a “security appliance” instead of just a “hardware firewall”, because the ASA is not just a firewall. This device combines several security functionalities, such as Intrusion Detection, Intrusion Prevention, Content Inspection, Botnet Inspection, in addition to the firewall functionality.

However, the core ASA functionality is to work as a high performance firewall. All the other security features are just complimentary services on top of the firewall functionality. Having said that, the purpose of a network firewall is to protect computer and IT resources from malicious sources by blocking and controlling traffic flow. The Cisco ASA firewall achieves this traffic control using Access Control Lists (ACL).

An ACL is a list of rules with permit or deny statements. Basically an Access Control List enforces the security policy on the network. The ACL (list of policy rules) is then applied to a firewall interface, either on the inbound or on the outbound traffic direction. If the ACL is applied on the inbound traffic direction (in), then the ACL is applied to traffic entering a firewall interface. The opposite happens for ACL applied to the outbound (out) direction.

The ACL permit or deny statements basically consist of source and destination IP addresses and ports. A permit ACL statement allows the specified source IP address/network to access the specified destination IP address/network. The opposite happens for deny ACL statements. At the end of the ACL, the firewall inserts by default an implicit DENY ALL statement rule which is not visible in the configuration.

Enough theory so far. Let us see some examples below to clarify what we have said above.

The basic command format of the Access Control List is the following:

ciscoasa(config)# access-list “access_list_name” extended {deny | permit} protocol “source_address” “mask” [source_port] “dest_address” “mask” [ dest_port]

To apply the ACL on a specific interface use the access-group command as below:

ciscoasa(config)# access-group “access_list_name” [in|out] interface “interface_name”

Example 1:

Allow only http traffic from inside network 10.0.0.0/24 to outside internet

ciscoasa(config)# access-list HTTP-ONLY extended permit tcp 10.0.0.0 255.255.255.0 any eq 80

ciscoasa(config)# access-group HTTP-ONLY in interface inside

The name “HTTP-ONLY” is the Access Control List itself, which in our example contains only one permit rule statement. Remember that there is an implicit DENY ALL rule at the end of the ACL which is not shown by default.

Example 2:

Deny telnet traffic from host 10.1.1.1 to host 10.2.2.2 and allow everything else.

ciscoasa(config)# access-list DENY-TELNET extended deny tcp host 10.1.1.1 host 10.2.2.2 eq 23

ciscoasa(config)# access-list DENY-TELNET extended permit ip host 10.1.1.1 host 10.2.2.2

ciscoasa(config)# access-group DENY-TELNET in interface inside

The above example ACL (DENY-TELNET) contains two rule statements, one deny and one permit. As we mentioned above, the “access-group” command applies the ACL to an interface (either to an inbound or to an outbound direction).

Example 3:

The example below will deny ALL TCP traffic from our internal network 192.168.1.0/24 towards the external network 200.1.1.0/24. Also, it will deny HTTP traffic (port 80) from our internal network to the external host 210.1.1.1. All other traffic will be permitted from inside.

ciscoasa(config)# access-list INSIDE_IN extended deny tcp 192.168.1.0 255.255.255.0 200.1.1.0 255.255.255.0

ciscoasa(config)# access-list INSIDE_IN extended deny tcp 192.168.1.0 255.255.255.0 host 210.1.1.1 eq 80

ciscoasa(config)# access-list INSIDE_IN extended permit ip any any

ciscoasa(config)# access-group INSIDE_IN in interface inside

Related posts:

1. How to Configure Access Control Lists on a Cisco ASA 5500 Firewall
2. How to Create and Manage Access Control Lists on Cisco ASA
3. Access Lists and NAT on Cisco ASA Firewalls. Some Clarifications

Again, I don’t recommend such a network topology as shown above. Remote Desktop machines are very prone to attacks, especially brute-force password attacks. In windows, the administrator account does not get locked-out by default. So a brute force administrator password attack on the RDP server from remote attackers can be successful especially if the administrator password is weak. In any case, if you are “forced” to implement such a scenario, here is the configuration:

ASA version prior to 8.3
ciscoasa(config)# static (inside , outside) tcp interface 3389 192.168.1.10 3389 netmask 255.255.255.255
ciscoasa(config)# access-list OUTSIDE-IN extended permit tcp any any eq 3389
ciscoasa(config)# access-group OUTSIDE-IN in interface outside

ASA version 8.3 and later
ciscoasa(config)# object network RDP_static
ciscoasa(config-network-object)# host 192.168.1.10
ciscoasa(config-network-object)# nat (inside , outside) static interface service tcp 3389 3389
ciscoasa(config)# access-list OUTSIDE-IN extended permit tcp any host 192.168.1.10 eq 3389
ciscoasa(config)# access-group OUTSIDE-IN in interface outside

NOTE: Notice that in version 8.3 we reference the Real IP address (192.168.1.10) in the access-list and not the mapped IP

Related posts:

1. Cisco Router with Cisco ASA for Internet Access
2. How to Configure Access Control Lists on a Cisco ASA 5500 Firewall
3. How to Configure Access Control Lists on a Cisco ASA 5500 Firewall

ACLs can be used to filter traffic for various purposes including security, monitoring, route selection, and network address translation. ACLs are comprised of one or more Access Control Entries (ACEs). Each ACE is an individual line within an ACL.

The syntax of an ACE is relatively straight-forward:

Ciscoasa(config)#access-list name [line number] [extended] {permit | deny} protocol

source_IP_address source_netmask [operator source_port] destination_IP_address

destination_netmask [operator destination_port] [log [[disable | default] | [level]] [interval seconds]] [time-range name] [inactive]

Here’s an example:

asa(config)# access-list demo1 permit tcp 10.1.0.0 255.255.255.0 any eq www

asa(config)# access-list demo1 permit tcp 10.1.0.0 255.255.255.0 any eq 443

asa(config)# show access-list demo1

access-list demo1; 2 elements

access-list demo1 line 1 extended permit tcp 10.1.0.0 255.255.255.0 any eq www

access-list demo1 line 2 extended permit tcp 10.1.0.0 255.255.255.0 any eq https

In the above example, an ACL called “demo1″ is created in which the first ACE permits TCP traffic originating on the 10.1.0.0 subnet to go to any destination IP address with the destination port of 80 (www). In the second ACE, the same traffic flow is permitted for destination port 443. Notice in the output of the show access-list that line numbers are displayed and the extended parameter is also included, even though neither was included in the configuration statements.

You can deactivate an ACE without deleting it by appending the inactive option to the end of the line.

As with Cisco routers, there is an implicit “deny any” at the end of every ACL. Any traffic that is not explicitly permitted is implicitly denied.

**Editing ACLs and ACEs**

New ACEs are appended to the end of the ACL. If you want, however, to insert the new ACE at a particular location within the ACL, you can add the line number parameter to the ACE:

asa04(config)# access-list demo1 line 1 deny tcp host 10.1.0.2 any eq www

asa04(config)# show access-list demo1

access-list demo1; 3 elements

access-list demo1 line 1 extended deny tcp host 10.1.0.2 any eq www

access-list demo1 line 2 extended permit tcp 10.1.0.0 255.255.255.0 any eq www

access-list demo1 line 3 extended permit tcp 10.1.0.0 255.255.255.0 any eq https

Notice in the first line of the example above that an ACE is added at line one in the ACL. Notice in the output from the show access-list demo1 command that the new entry is added in the first position in the ACL and the former first entry becomes line number two.

You can remove an ACE from an ACL by preceding the ACE configuration statement with the modifier no, as in the following example:

Asa04(config)#no access-list demo1 deny tcp host 10.10.2.1 any eq www

In my next article, I’ll show you how to use time-ranges to apply access-control lists only at certain times and/or on certain days. I’ll also show you how to use object-groups with access-control lists to simplify ACL management by grouping similar components such as IP addresses or protocols together.

Copyright (c) 2008 Don R. Crawley

Don R. Crawley, CCNA-certified, is president and chief technologist at soundtraining.net, the Seattle training firm specializing in business skills and technical training for IT professionals.

Article Source: http://EzineArticles.com/?expert=Don_R._Crawley

Related posts:

1. How to Configure Access Control Lists on a Cisco ASA 5500 Firewall
2. How to Configure Access Control Lists on a Cisco ASA 5500 Firewall
3. Access Lists and NAT on Cisco ASA Firewalls. Some Clarifications